A&P 1 exam 2 (part 6)
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A&P 1 exam 2 (part 6)
exam fall 2014
Human Embryonic Development Human Embryonic Development 2 Fall 2014
acquiring specialization, but loose potential
in differentiation, once you start down one path ?
you cant go back
path of embryonic development order?
has specialization and cant give rise to any other cell
occurs during 1st 8 weeks, ground work has been layed for systems to develop
formation and maturing of systems, last 32 weeks, period of growth
during the embryonic period what is developed?
basic body plan is established
body tube consists of?
empty space inside tube
epithelium that line coelom
sanwhiched between skin and serous membrane
gut tube is found?
gives rise to internal organs, systems are derived from gut tube
gut tube is covered with? which is a
dorsal body wall ?
nervous system inside vertebral column which is located in midline
midline of dorsal body wall is made up of?
vertebrae and nerve cord
where are kidneys found?
embedded in dorsal body wall behind coelom
why are kidneys special?
they come from different location that the others, that come from gut tube
limbs aren't tubes bc?
they have skeletal system down the middle
limbs are made of
skin of limbs?
muscle of limbs?
in between skin and skeletal
bone of limbs?
skeletal is aka
early events of development?
largest cell found in humans
fertilized egg in coelom
sperm changes of succeeding?
millions are produced every day
only cell with flagella, used to move
sperm head? tail?
head carries DNA
tail is the flagellum
every time cell divides, it is only?
1/2 the size which dramatically alters cell physiology
cell division is an
cell divides but 2 daughter cells are only 1/2 size
flow of early cleavage?
embryo is a solid ball of about 100 cells
take 4 days to get to this stage
ball of cells develop a cavity, hollow cell
arrives at uterus for implantation
surrounded by single layer of cells
space that trophoblast encloses
clump of cells inside trophoblast
inner cell mass (ICM)
blastocyst is made of?
inner cell mass
embryo only develops?
some of the cells of ICM
what does trophoblast contribute to?
development of placenta (extracellular)
what happens during implantation?
blastocyst arrives at uterus and needs to implant, does this by burrowing into side of wall of uterus and begins to set up placenta
what happens immediately once blastocyst burrows into wall of uterus?
begins to set up placenta
develops from some cells of bilaminar disk? what are others known as?
inner cell mass has developed?
2 spaces surrounded by cells
groove cut down middle of ectoderm
slight swelling of cells at primitive streak
don't need yolk bc nutrients come from placenta, do need cells that make up ____ ___
double layer of cells?
has a cellular grade organization where tissue is organic
surround amniotic sac
surrounds yolk sac
both are tissues and primary germ layers
ectoderm and endoderm
cells of ectoderm migrate to ?
individualy separate off epithelial sheet they migrate out laterally and a 3rd layer between ectoderm and endoderm
cells of ectoderm migrate to primitive streak
once ectoderm migrates to primitive streak, then you have trilaminar disk
primary germ layer
layer between ecto and endoderm
freely migrating embryonic cells
not all mesoderm is ____ and not all _____ is mesoderm
trilaminar disk is made of?
ectoderm of trilaminar disk forms?
endoderm of trilaminar disk creates?
gut tube and internal organs
mesoderm of trilaminar disk creates?
muscular and skeletal system
the 1st structures seen found in mesoderm are ?
1st structure formed from mesoderm?
notochord is formed right down?
midline of embryo
condensed solid rod
a temporary embryonic structure that acts as a structural, rigid support
notochord is eventually replaced by?
seperates mesoderm into 2 groups
what is derived from notochordal cells
in differentiation of mesoderm cells adjacent to notochord begin to condense into solid blocks aka
mesoderm found in somites
mesoderm thins out into a thin sheet
undergoes differentiation and develops space that is separated into 2 parts
lateral plate mesoderm
2 types of lateral plate mesoderm?
pressed up against ectoderm
pressed up against endoderm
space between somatic and splanchnic mesoderm
folds that continue to elevate towards a point and more directed towards midline
at the neural grooves, cells beings to
gives rise to central nervous system
form mesenchyme at same time as
the neural tube is arranged as?
epithelial, one continuous structure
different cellular organization than tube, freely migrating embryonic cells and is not attached to other cells
spread out all through body
the neural crest is important to the formation of ?
development and some skeletal elements, also forms ALL sensory nerve cells
at nervous system stage, embryo begins to ?
roll into tube by closing in lateral body wall
closing in wall and becomes wrapped with ectoderm, while endoderm forms a tube inside
lateral body wall
close in head and tail end, the rolling comes in from all directions converging on ventral sides of embryo
anterior and posterior body wall
once body shape is formed, at this stage we have?
body organization--- tube within a tube design
ectoderm gives rise to
epidermis of skin and skin glands, outerlayer of gut tube
tube with in tube (gut tube)
inner layer of gut tube
respiratory system (lungs)
blocks of mesoderm that differentiate into 2 distinct populations of cells as ultimate fate
3 distinct populations of cells that somites create?
leave somite, migrate out and spread out underneath ectoderm
what does dermatone give rise to?
both sides migrate towards center and surround neural tube
sclerotone gives rise to?
when notochord is replaced, what is the only remnant left?
cells spread out and give rise to muscles in body wall
most is lost, but posterior section gives rise to kidneys and gonads
lateral plate mesoderm is differentiated into ?
2 as ultimate fate
gives rise to muscles of gut and serous lining of gut
serous lining of body wall
space between splanchnic and somatic mesoderm
ectoderm limb buds?
gives ride to epidermis, form pockets
mesoderm of limb buds
migrate into pockets and give rise to muscle and bone and dermis
after 40 days what is formed?
hand --- has paddle like appearance
after 54 days what is formed?
hand is recognizable